SAPHO syndrome

Psoriatic arthritis (PsA) is a seronegative spondyloarthritis that develops in up to 30% of patients with psoriasis, producing asymmetric oligoarthritis or distal interphalangeal joint disease, dactylitis, enthesitis, nail dystrophy, and axial involvement. Diagnosis is clinical, supported by the CASPAR criteria. Limited peripheral disease is treated with an NSAID or intra-articular glucocorticoid, more active disease with methotrexate, a tumor necrosis factor inhibitor, or an interleukin-17 inhibitor.

Ankylosing spondylitis is the radiographic axial spondyloarthritis: a chronic, HLA-B27-associated inflammatory disease of the sacroiliac joints, spine, and entheses presenting with inflammatory back pain before age 45. Sacroiliitis on pelvic radiograph or MRI establishes the diagnosis. First-line treatment is continuous scheduled NSAIDs with active exercise, escalating to a tumor necrosis factor inhibitor, then an interleukin-17 inhibitor, when NSAIDs fail.

Reactive arthritis is a sterile, human leukocyte antigen B27 (HLA-B27)-associated spondyloarthritis that follows a genitourinary or enteric infection by 1 to 4 weeks, producing asymmetric lower-limb oligoarthritis, enthesitis, and the urethritis-conjunctivitis-arthritis triad. It is a clinical diagnosis of a culture-negative joint. First-line treatment is an NSAID such as piroxicam for at least 2 weeks, escalating to glucocorticoids and then sulfasalazine or a tumor necrosis factor (TNF) inhibitor for disease persisting beyond 3 to 6 months.

Osteomyelitis is bone infection from hematogenous seeding or contiguous spread, most often from Staphylococcus aureus, presenting as subacute pain with or without a draining sinus tract and confirmed by bone biopsy culture. Empiric antibiotics are withheld until biopsy in a stable patient, and treatment combines source control with 4 to 6 weeks of culture-directed antibiotics, extended to 6 weeks or indefinite suppression for hardware-associated or chronic disease.

Osteomyelitis is bone infection from hematogenous seeding or contiguous spread, most often from Staphylococcus aureus, presenting as subacute pain with or without a draining sinus tract and confirmed by bone biopsy culture. Empiric antibiotics are withheld until biopsy in a stable patient, and treatment combines source control with 4 to 6 weeks of culture-directed antibiotics, extended to 6 weeks or indefinite suppression for hardware-associated or chronic disease.

Acne vulgaris is a chronic inflammatory disorder of the pilosebaceous unit producing comedones, papules, pustules, and in severe disease nodules and scarring on the face, chest, and back. First-line treatment is a topical retinoid, escalating through topical or oral antibiotics paired with benzoyl peroxide, hormonal therapy, or oral isotretinoin as severity and scarring dictate.

Psoriasis is a chronic, relapsing, immune-mediated dermatosis of accelerated keratinocyte turnover, classically presenting as sharply demarcated, silvery-scaled plaques on extensor surfaces, with guttate, inverse, pustular, and erythrodermic variants and an associated psoriatic arthritis. Mild-to-moderate disease is treated with emollients and topical corticosteroids with or without a vitamin-D analogue (calcipotriene 0.005% twice daily), while widespread (over 10% body surface area), recalcitrant, or severe disease escalates to phototherapy, methotrexate (weekly single dose 7.5 to 25 mg), or a biologic such as adalimumab, ustekinumab, or secukinumab, never a systemic glucocorticoid.

Septic arthritis is bacterial infection of a joint, most often Staphylococcus aureus seeding the knee hematogenously, and is a medical and surgical emergency diagnosed by expeditious arthrocentesis showing a synovial leukocyte count generally above 50,000/microliter. Treatment combines empiric intravenous antibiotics such as vancomycin plus ceftriaxone with urgent joint drainage, since delayed source control destroys cartilage within days.

Rheumatoid arthritis is a chronic systemic autoimmune disease causing symmetric small-joint polyarthritis of the hands and feet that spares the distal interphalangeal joints, with morning stiffness over an hour. Diagnosis combines the ACR/EULAR classification criteria with rheumatoid factor, anti-CCP antibody, and radiographs. Treat-to-target management anchors on methotrexate, escalating to a biologic or targeted synthetic disease-modifying antirheumatic drug when remission is not reached.

Nonsteroidal anti-inflammatory drugs (NSAIDs) relieve pain, fever, and inflammation by inhibiting cyclooxygenase (COX)-1 and COX-2, and that single mechanism predicts every major toxicity: gastric ulceration, platelet dysfunction, and hemodynamic renal injury. First-line agents are naproxen or ibuprofen (or topical diclofenac for knee or hand osteoarthritis) at the lowest effective dose for the shortest duration, with a proton pump inhibitor such as omeprazole 20 mg once daily added for patients at increased gastrointestinal risk.

Paget disease of bone is a common, localized disorder of accelerated, disorganized bone remodeling that raises serum alkaline phosphatase with normal calcium and phosphate, usually diagnosed incidentally, and treated with a single dose of intravenous zoledronic acid when bone pain, high-risk sites, or marked alkaline phosphatase elevation are present.